Duplicating machine



5 Sheets-Sheet l H. CARSON ET AL DUPLIYCAT ING MACHINE Oct. 11, 1949.

Filed 001,52, 1944A 7&1 ATTORNEY# @yf www N d. E mm B w ,w L 5 Z wm w a33 5 35 7 @l 5 0 G I Z a ah z Il l .1 0 2J .lh 1,0/2 W a M z W7@ 1v 8 MP Oct. 1l, 1949.

Filed Oct. 2, 1944 H. CARSON ET AL DUPLICATING MACHINE 4 3 Sheets-Sheet2 ATTORNEY/ Oct. 11, 1949. H. CARSON ETAL 2,484,553

DUPLICATING MACHINE 7i t l VENTORS y @j @fw 7250; ATTORNEY Patented Oct.11, 1949 DUPLICATING MACHINE Howard Carson, Howard M. Geyer, and JamesW. Light, Dayton, Ohio, assignors to General Motors Corporation,Detroit, Mich., va corporation of Delaware Application October 2. 1944,Serial No. 556,702

8 Claims. (Cl. Sil-24.3)

'I'his invention relates to the art oi' planing metal, and moreparticularly to a duplicating mechanism by which a surface of a patternis automatically reproduced on a workpiece by a metal planer. The typeof duplicating mechanism to which the present invention relatescomprises an hydraulic servomotor for positioning the planer tool holderand means for controlling the servo-motor comprising a ported membermovable with the workholder and a valve cooperating with the member andconnected with a pattern follower member. When the duplicator is usedwith a planer having a horizontal movable bed, the pattern and theworkpiece are mounted side by side on the planer bed, the pattern beingengaged by the follower and the workpiece by the tool. As the planer bedmoves the workpiece against the tool, the follower moves verticallyaccording to the contour of the pattern and effects vertical movement ofthe tool holder equal to and in the same direction as the verticalmovement of the follower.

It is an object of the invention to provide a duplicator for a metalworking machine, such as a planer, which is of durable and economicalconstruction and which is sensitive and stable in operation.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

Fig. 1 is a perspective view of the duplicating mechanism. y

Fig. 2 is a fragmentary view showing the manner in which the valvecontroller follows a pattern having a relatively steep slope. l

Fig. 3 is a perspective view partly in section of the ported valvemember and enclosed valve for controlling the servo motor of theduplicating mechanism.

Fig. 4 is an hydraulic diagram.

Fig. 5 is an enlarged view showing the valve in section assembled in thepiston.

Fig. 6 is a front view of the controller looking in the direction of thearrow` 6 of Fig. 1, the part in section being on line 6-6 of Fig. '7.

Fig. 7 is a sectional view on line 1-1 of Fig. 6.

Fig. 8 is a diagram which denotes stability of Aoperation of themechanism.

Referring to Fig. 1, P denotes the pattern and W the workpiece, thesemembers beingmounted on the horizontally reciprocating bed (not shown) 2P and W to move in the direction of the arrow A for cutting and in thereturn direction indicated by arrow B. As the planer bed moves in thedirection of the arrow A, the workpiece W moves against a cutting toolI0 mounted in a holder I I which is pivotally connected at I Ia with asupport I2 which is guided by ways I3 provided by a plate I4 which iscarried by a slide I5. By a screw and nut mechanism (not shown) theplate I4 may be adjusted vertically relative to the slide I5. The slideI5 is supported for horizontal movement on a bar I6 which is supportedby the frame of the planer. During motion of the bed in the direction ofthe arrow A, the slide I5 remains fixed; and, during movement of theplaner in the direction of the arrow B, the slide I5 is caused to move apredetermined distance to the right in order to locate the tool I0 inposition for a new cut. The feeding of the block I 5 is effected in awell known manner, such as by means of a nut and screw mechanism, thescrew being indicated by the numeral I1.

It will 4be understood that the planer controls the horizontal movementof the tool l 0 in a horiof a metal working vplaner which causes the 55zontal direction as represented by the arrow H (Fig. 1), while thevertical movements of the tool as indicated by the arrow V arecontrolled by the pattern P which is engaged by a follower which is a,segment of a hollow sphere. The follower 20 is urged by a tensionspring 2| attached thereto against a ball 22 (Figs. 2 and 3) provided bythe end of a rod 23 extending downwardly from a flange 1,4 (Fig. 7)which, together with a leaf spring 25, is fastened to a flange 26integral with sleeve 21 having a lug 28. The rod 23 extends through thesleeve 21 and receives a nut '23a which clamps to the sleeve 21 a leafspring 29, which, together with a bracket 3U is secured by screws 3| toa valve housing 32. The screws 33 pass through spring and spacer sleeves33a and are threaded into housing 32. Sleeves 33a determine the distancebetween the fixed ends of the leaf springs 25 and 29.

A valve is urged downwardly by fluid-pressure means, to be described,against the nut 23a.

Valve 40 is slidable within a ported valve guide located within thehousing 32. The valve 40 is provided with flanges 4I and 42 engaging theguide 50 near the upper and lower ends thereof and with valve lands 43and 45 which respectively control ports 53a, 53h and 55a, 55h of the'guide 50. The ports 53a, 53h communicate with an annular channel orgroove 53e which, by passages (not shown) in the housing 32 and by a11.05 53d (Fig. 1), is connected with the lower end 8 v of a cylinder 80as shown diagrammatically in Fig. 4. vThe ports 55a, 55h communicatewith a groove 55e which by passages (not shown) provided in the housing32 and by a hose 55d, is connected with the upper end of the cylinder80. Cylinder 80 receives a piston 8| (Fig. 4) connected by rod 82 withthe tool holder support I2 (Fig. 1)`.

The valve guide 50 provides cylinder drain ports 52 and 56 communicatingrespectively with grooves 52e and 56e which, as shown in Fig. 4, areconnected together by vhorizontal passages 52h and 56h and by verticalpassage 51 with an opening 56a which is connected by hose 56d with valveseat 56e closed by a check valve 56j and .communicating with the tank Tcontaining the hydraulic pressure fluid, the level of which is indiecated at I. per square inch on the discharge line 56d.

In Fig. 4, a pump 80 forces liquid under high pressure past a checkvalve 6| through a hose 54d connected with a groove 54e of valve guide50 which is connected by ports 454 with the central bore of the guide50. The pump 80 is connected by pipe 62 with an accumulator 63 having adiaphragm 64; and pipe 62 is connected with the tank T by a vbranch pipe65, the outlet of which is controlled by a spring-loaded valve 66. Valve66 maintains 700-800 lbs. per square inch pressure in pipes 62 and 54d.The chamber 64a is viilled with air or nitrogen at 300 lbs. per squareinch pressure through a tube closed by a tirevalve 64b.

A low pressure pump 10 is connected with a by-pass 1| controlled byvalve 12, loaded for 15-20` lbs. per square inch pressure, and with ahose |d (Figs. 1 and 4) connected by pipe tting 5|e with a passage 5|cprovided by a block -15 attached to the housing 32. Communicationbetween passage 5|c and a passage 5 la is controlled by a needle valve5|b on the end of a screw 18 threaded through a bushing 18a threadedinto the block 15. Screw 18 has a knurled head 11 frictionally engagedby a spring'16 xed to block 15. Passage 5|a connects with a centralrecess 5| in block 15, said recess being closed by the ange 4| of thevalve 40, said flange functioning as a piston to receive the lowpressure iiuid in the cylinder 5|.

It is important that air be excluded from the hydraulic system. Duringfilling with pressure oil, a plug 80a (Fig. 4) in cylinder 80 isremoved. By means of a screw-driver passed down through thevunpluggedhole, a valve 81h in piston 8| is turned to open a port Bla through thepiston (Fig. 4). The recess 5| is provided with a vent passage 19controlled by an air bleed valve 19a l which is open while this recessis being filled with pressure oil. After the system is filled tooverflowing, valve 8| b is closed, plug 80a is applied, and valve 19a isclosed. As shown in Fig.

7, a rod 93 provides'the vent passage 19 and a plug 19a provides thevalve for closing it.

'I'he valve guide50 is retained within the housing 32 bythe plate 15which is attached to the 1 upper end ofthe housing and by a bracket 85attached to the lower end of the housing. The

bracket 85 supports a shaft 86 carrying an eccentric cam 81 forengagement with the lug 28 1 of sleeve 21 when the shaft is rotated bymoving a lever 88 connected with the shaft 88 upwardly for the purposeof moving the valve upwardly from the position shown in Figs. 3, 4 and'7 to such position as to place port 53a in communication with port 54so that the lower end of the 1 cylinder 80 will receive pressure fluidwhile the upper end is connected with drain order that the tool l0 willbe retracted from the work W.

Valve 561 maintains 15 to 20 lbs In other words. when the lever 88isrotated 180 -from the position shown, the piston 9| operates toretract the tool I0 from the work W. When the cam 81 does not engage thelug 28, and when there is no pressure in the system, the springs 25, 29normally hold the valve 40 about .010

inch above -neutral position. Leakage between the recess 5| (Fig. 3) andthe groove 52e is prevented by packing ring |30 located in a groove |3|provided by the plate 15. The leakage between the several grooves 52a,53a, 54a, 55a and 56a and between the groove 55a and the lower end otthe housing 32 is prevented by other packing rings |32 received bygrooves provided by the valve guide 50.

The valve housing 32 is provided with a cylindrical portion 90 eccentricwith the valve 40; and

this cylindrical portion is received within the cylindrical bore of ablock 9| which is split at 92 so that the bracket 9| may serve as aclampwhich can be tightened around the cylindrical portion 90 of housing 32by the tightening of a screw 92a, thereby securing the housing 32 to theblock 9| in a desired position of vertical adjustment relative thereto.In order to provide for this vertical adjustment, there is attached tothe plate 15 the threaded rod 93 extending through a nut 94 (Fig. 6)connected by pin 94a with a knurled ring 94h. Nut 94 and ring 94h arespaced vertically by the yoke of a bracket 95 shaped like an inverted Uand attached by screws 95a to the block 9|. The plate 15 iits betweenthe vertical arms of the bracket 95 so that rotation thereof isprevented while turning the nut 94, by means of the knurled ring 94h, inorder to raise or lower the rod 93 and the valve housing 32 while theblock 9| is unclamped from the housing 32 by loosening the screw 92a.After the housing 32 has been adjusted vertically relative to the block9|, the screw 92a is tightened.

Block 9| has a cylindrical portion `|00 (Fig. r'1) slidable through ahorizontal bore in a block |02 having avkey-way |03 receiving a key |04attached to part |00. To block |02 is attached a bracket |05 whichspaces a iiange |06 of a screw |01 from the hub |08 of a knurled head|09 atpasses loosely through the yoke of bracket |05 and threadedlyengages the part |00 of block 9|. By turning the screw head |09 theblock 9| and the follower 20 (Fig. l) can be adjusted horizontally inthe direction of arrows A or B. When the adjustment is made, the block|02, which is split at`|02a, can be clamped around the part I 00 ofblock 9| by tightening a screw |02b.

The block |02 is adjustable horizontally (at right angles to directionsA- or B) relative to a bracket |20 and is secured thereto in therequired position of adjustment by the tightening of a screw |20a.Bracket |20 is secured to tool holder support I2 by members |2| and |22.Therefore the tool andthe valve housing 32 and the valv guide 50 move asa unit.

lThe system consists essentially of a source of v hydraulic power (thepump 60) a four-way valve the top of cylinder is connected through ports55a and 58h and It and by pipe 88d 'and drain valve 56j with tank T.With valve 40 so located, the pressure in the bottom of cylinder 8|!forces piston 8| upwardly. Since the valve guide 5U is connected to thepiston Il. through support l2 and rod 82, the guide 5!! moves up withthe piston 8| and ports 58a, 53h and 55a, 55h become closed by lands I3,I5 of valve 48. This results in a new equilibrium position of the piston8| corresponding to the new position of the valve Ill.

Since the lowering of valve 40, as the pattern P traverses it, willresult in the lowering of the piston 8| by the reverse of the actiondescribed in the preceding paragraph, it is apparent that the piston 8|will continually follow the vertical movements of the valve l0 as thefollower 20 is traversed by the pattern P. As the forces that can beexerted by hydraulic pressure on the piston 8| are very great comparedto that necessary to deflect the valve 40 from its equilibrium'position, it is apparent that a. relatively large amount of poweramplification is obtained. It is of great advantage to be able to exertrelatively large forces upon the tool holder to raise and lower it andto hold it fixed, while the tracer 20 is exerting relatively lightpressure upon the pattern P.

In order to obtain the greatest possible accuracy of duplication betweenthe master pattern and the work, it is essential that the four-way valve(valve 40, guide 50) be very sensitive t0 deflections of the valve l0.That is, for very slight deflections of the valve 40, there should be aconsiderable change in pressure on the end of piston 8| in order thatmotion of piston 8| start to bring the valve guide 50 to a position ofequilibrium. It has been found that the most sensitive type of four-wayvalve is one which has negative overlap between the lands of the valveand the .ports of the valve guide. To obtain this negative overlap, itis necessary that the valve lands be slightly shorter than the totalport width of the valve guide. Therefore land I3 is slightly less inwidth than the distance between the lowest portion of port 53a and thehighest portion of port 53h and land 45 is slightly less in width thanthe distance between the lowest portion of port 55h and the highestportion of port 55a. This arrangement results in a slight bleeding ofthe oil from pump il to the sides of the piston 8| and a slight bleedfrom both these sides to drain. This use of negative overlap results ina pressure on both sides of the piston 8| equal to about one-half thesupply pressure from the pump 60 when the system is in equilibrium.Slight deflections of the valve 40 will result in pressure decrease onone side of piston 8| and pressure increase on the other side and,consequently a movement of the valve guide 50 to bring its ports into aposition of equilibrium relative to valve 40 when the preslures onboth`sides of the piston 8| will be equal again.

It has been found that the use of a sensitive four-way valve, such asdescribed, results in instability of control. To beable to use asensitive valve and yet retain stability, the valve 40 is urged towardthe pattern by hydraulic pressure supplied by pump 10 at 15 to 20 lbs.per square inch upon the piston portion 4| of valve 40 which closes therecess or cylinder 5| in the housing' cover plate 15. A total pressureof ve pounds on the tracer has been found satisfactory. If too little,the tracer will not follow the pattern closely; and, if too great, thepattern, if made of wood, will be unduly worn. The rate of flow of fluidinto or out of the cylinder 5| through passage ila is controlled byneedle valve IIb which is adjusted to give the correct amount of dampingeffect or retardation of the rate of movement of valve 4l relative tovalve guide III. Stability is increased by increasing the dampingeffect. The response cf the tracer 28 to the elevations and depressionsin the moving pattern P is retarded somewhat" but the response is stillfast enough for normal duplicating operations such as for shaping anairplane propeller blade. For proper functioning of the stabilityproducing means, all air must be excluded from the space between thepiston 4| and the valve Mb, that is, in the cylinder Il and passage tia.Therefore the vent 18 must be tightly closed after being lled with oil.

The test of stability is by what is known the step function: In Fig. 8,the horizontal represents time and the vertical represents deflection.A-B represents a sudden drop of the follower 20. A--C represents thedrop of the tool ||l by piston 8| and also the drop of the valve guide50. Without stability control, the tool will vibrate vigorously asindicated by the dot-dash wavy line C-D which represents vibrations at10 to 15 cycles per second which continued for some time. With stabilitycontrol Vas provided by hydraulic damping in the manner described,vibration of the tool is promptly damped as indicated by full line C-Ewhich shows that stability is attained in a small fraction of a secondafter the drop A to B. If the apparatus can pass the step function sta-'bility test by producing the damping eii'ect of line C--E, theapparatus performs satisfactory duplication.

The springs 25 and 29 which support the tracer or follower 20 provide arigid support preventing movement of the follower 20- in all directionsexcept the vertical without introducing friction. Hence, only a smallforce in opposition to these springs is required to move the follower 20in the direction of movement of the valve 40.

The hydraulicloading of the valve 40 provides a safety feature whichprevents the digging of the tool into the work vin case of failure ofthe pumps to supply pressure fluid. The pumps l0 and 1l may be drivenfor example by electric motors. In case of cessation of electricalpower, the pumps will stop. The pressure in cylinder 5| upon valvepiston 4| will cease. Springs 25 and 28 lift the valve 40 about .010inch above equilibrium position which is sufficient to block ports 55aand ,55h from pressure in pipe 54d and to connect Md with the lower sideof piston 8|. The tool is raised from the work by virtue of hydraulicpressure created by the air or gas pressure of 300 lbs. per square inchstored in the accumulator chamber a acting against diaphragm M, saidpressure being retained by check valve 8| and by spring closed valve 8iwhich can open only at pressure of '700 lbs. to 800 lbs. per square inchor greater. The capacity of the accumulator is suflicient to give timefor stopping the planer and to provide some other means for the supportof the tool above the work.

It is desirable to be able to duplicate from a relatively soft woodenmaster pattern such as one made of mahogany or other wood rwhich retainsits shape. For accurate duplication, the follower or tracer 2l shouldhave an effective radius equal to the radius of the plane of the cuttingedge of the tool I0 which, foi` example, may be only .125 inch. If thetracer were only the ball 22 (Figs. 2 and 3) having this radius, awooden pattern would become grooved quickly and rendered unfit for usebecause the unit presassassins unit pressure can be reduced to a value`such that grooving the pattern becomes practicallynegligible by using atracer 20 in the form oi' a spherical cup of about one-haii'vinchradius. The cup Il is .030 inch thick and the radius of the ball 22is .095 thus making the eii'ective radius of the tracer .125 inch whichis equal to the radius of the plane 4 of the cutting edge of the toolIl.

As the radius of the cutting tool `I in the direction of work motion(arrow A in Fig. 1) is very small (practically a sharp point) some erroris introduced in duplicating, especially when the tracer engages arelatively steep slope of the pattern as indicated in Fig. 2, due to thefact that the tracer has a definite radius. With the ball and cuptracer, this error is considerably reduced from that which would occurif a roller type tracer were used.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A duplicating mechanism comprising a tracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, -an hydraulic servo for positioning the tool-holder andcomprising piston and cylinder members, one being stationary and theother being connected with the tool-holder, a valve for controlling theadmission of pressure fluid to the servo cylinder, said valve comprisinga ported valve guide attached to the tool-holder and a port-controllingvalve actuated by the tracer.

fluid pressure operated means for urging the` tracer against the modeland means for limiting the rate of fluid pressure circulation withrespect to said means in order to limit the rate of relative movementbetween the valve and the valve guide in order to dampen vibration ofthe tool-holder.

2. A duplicating mechanism comprising a tracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, an hydraulic servo for positioning the tool-holder andcomprising piston and cylinder members, one being stationary and theother being connected with the tool-holder, a valve for controlling theadmission of pressure iiuid to the servo cylinder, said valve comprisinga ported valve guide attached to the tool -holder and a portcontrollingvalve actuated by the tracer, iiuid pressure operated means for urgingthe valve .against the tracer and the tracer against the model andcomprising a piston connected with the valve and a cooperating cylinderprovided by the valve guide, and means for restricting the iiow ofpressure iluid between the cylinder and a pressure uid source in orderto limit the rate of relative movement between the valve and `the valveguide in order to'dampen vibration of the tool-holder.

3. A duplicating mechanism comprising a ltracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, an hydraulic servo for positioning the tool-holder andcomprising piston and cylinder members, one being stationary and theother being connected with the tool-holder, a valvefor controlling theadmission of pressurefluid to the servo cylinder, said valve comprisingaported valve guide attached to the tool-holder and Va port-controllingvalve actuated by the tracer, fluid pressure operated means for urgingthe 8 tracer against the model, and spring means opposed thereby andacting, upon cessationv of fluid' pressure upon said means. to move thetracer away fromthe model and to position the valve for `eectlng,through the hydraulic servo, a movement oi! the tool-holder away fromthe work. u

4. A duplicating mechanism comprising a tracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, an hydraulic servo for positioning the tool-holder andcomprising piston and cylinder members, one being stationary and theother being connected with the tool-holder, a valve for controlling theadmission oi' pressure uid to the servo cylinder, said valve comprisinga ported valve guide attached to the tool-holder and a port-controllingvalve actuated by the tracer, fluid pressure'operated means for urgingthe tracer against the model, spring means opposed thereby andacting-upon cessation oi' fluid pressure upon said means, to move thetracer away from the model and to position the valve for effecting,through the hydraulic servo, a movement of the tool-holder away from thework, a source of fluid pressure for operating the hydraulic servo and apressure uid accumulator charged by the fluid pressure source andacting, upon cessation of operation of said fluid pressure source, tosupply pressure uid to the hydraulic servo in order that the tool-holderwill be moved away from the work. Y

5. A duplicating mechanism comprising a tracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, an hydraulic servo comprising a cylinder and a pistonconnected with the toolholder, a, high pressure uid source, a four-waythe source and the other end with drain or vice versa, said valvecomprising a tubular, ported valve guide attached to the tool-holder anda valve actuated by the tracer and having lands controlling the ports ofthe valve guide, a low.

pressure fluid source, and means operated thereby for urging the traceragainst the model, said means including a cylinder provided by the valveguide and a piston provided by the valve.

6. A duplicating mechanism comprising a tracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, an hydraulic servo comprising a cylinder and a pistonconnected with the toolholder, a high pressure iluid source, a four-wayvalve for connecting one end of the cylinder with the source and theother end with drain or vice versa, said valve comprising a tubular,ported valve guide attached tothe tool-holder and a valve actuated bythe tracer and having lands controlling the ports .of the valve guide, alow l pressure uid source, means operated thereby for tracer -forengaging a model to be duplicated, a tool-holder for supporting a toolwhich operates upon the work, an hydraulic servo comprising a cylinderand a, piston connected with the toolholder, a high pressure fluidsource, a four-way valve for connecting one end of the cylinder with thesource and the other end with drain or vice versa, said valve comprisinga tubular, ported valve guide attached to the ytool-holder and a valveactuated by the tracer and having lands controlling the ports of thevalve guide, the arrangement of the ports and lands being such th.a.t,in the equilibrium position of the valve, the high pressure fluid sourceis connected with both ends of the cylinder and with drain, thework-holder being held fixed, a low pressure source, and means operatedthereby for urging the tracer against the model, said means including acylinder provided by the valve guide and a piston provided by the valve,and means for limiting the rate of movement of the low pressure fluidwith respect to said last named cylinder in order to limit the rate ofrelative movement between the valve and valve guide thereby to dampenvibrations of the work-holder.

8. A duplicating mechanism comprising a tracer for engaging a model tobe duplicated, a tool-holder for supporting a tool which operates uponthe work, an hydraulic servo comprising a cylinder and a pistonconnected with the toolholder, a high pressu.e uid source, a four-wayvalve for connecting one end of the cylinder with the source and theother end with drain or vice versa, said valve comprising a tubular,ported valve guide attached to the tool-holder and a valve actuated bythe tracer and having lands controlling the ports of the valve guide,the-arrangement of the ports and lands being such that, intheequilibrium position'of the valve, 4the high pressure uid source isconnected with both ends of the cylinder and with drain, the workholderbeing held lixed, means for urging the tracer toward the model and meansfor limiting the rate of relative movement between the valve and valveguide thereby dampening vibrations of the work-holder.

HOWARD CARSON.

HOWARD M. GEYER.

JAMES W. LIGHT.

REFERENGES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 2,046,013 Bingel et al June 30,1936 2,101,712 Johansen Dec. 7, 1937 2,154,718 Bannon Apr. 18, 1939 Re.21,544 Richard Aug. 27, 1940 2,349,171 Jackson May 16, 1944 2,376,405Turschan et al May 22, 1945

